Hastings, 2.745" bore piston ring set. +.040"

Past op: 29-49 45" (750cc) Flathead (NU)

Comes with parkerized cast gray iron compression and oil rings. Used with early style 1929-1949 type pistons with the one-piece cast iron oil ring.
Std cyl. bore: 2.745" (69.72mm).
1st ring: 2.3mm (3/32).
2nd ring: 2.3mm (3/32').
Oil ring: 3.2mm (1/8").

Note: OEM 1950-1973 pistons are equipped with 1/16" (1.6mm) 1st. & 2nd rings and late style 3/16" (4.75mm) 3-piece flex-vent style oil rings for improved oil control, for these Hastings rings see 1950-1973 Flathead model years. Above mentioned rings will not fit the 1950-1973 new type pistons.
Tech tip: Piston grooves vs piston rings.
It's not difficult to determine if a Hastings piston ring set will fit a certain piston. You should measure the height of the piston groove in the piston itself. The 2 top grooves will be for compression rings, the lower groove will be for the oil ring. In most cases Hastings oil rings are of the low tension 3-piece flex vent type. Ring heights are listed for reference.
Tech tip: Piston oversizes.
For each oversize cylinder diameter will increase with .010" (0.254mm). The standard bore of the cylinder is listed for reference.
(Tech tip information provided by Hastings Manufacturing Company, Inc.)